Abstract: A turbomachine airfoil element includes an airfoil that has pressure and suction sides spaced apart from one another in a thickness direction and joined to one another at leading and trailing edges. The airfoil extends in a radial direction a span that is in a range of 27.5-28.5 inches (699-724 mm). A chord length extends in a chordwise direction from the leading edge to the trailing edge at 50% span and is in a range of 13.0-14.0 inches (330-356 mm). The airfoil element includes at least two of a first mode with a frequency of 34±10% Hz, a second mode with a frequency of 90±10% Hz, a third mode with a frequency of 178±10% Hz, a fourth mode with a frequency of 222±10% Hz, a fifth mode with a frequency of 307±10% Hz and a sixth mode with a frequency of 389±10% Hz.

Abstract: An electroformed sheath for protecting an airfoil includes a sheath body and a mandrel insert is provided. The sheath body includes a leading edge. The sheath body includes a pressure side wall and an opposed suction side wall, which side walls meet at the leading edge and extend away from the leading edge to define a cavity between the side walls. The sheath body includes a head section between the leading edge and the cavity. The mandrel insert is positioned between the pressure side and suction side walls, and includes a generally wedge-shaped geometry. A method for protecting an airfoil includes: 1) securing a mandrel insert to a mandrel; 2) electroplating a sheath body onto the mandrel and the mandrel insert; 3) removing the mandrel from the sheath body so that a sheath cavity is defined within the sheath body; and 4) securing the airfoil within the sheath cavity.

Abstract: A blade for a gas turbine engine. The blade having: an airfoil formed from a first material; a protective sheath disposed on a leading edge of the airfoil, the protective sheath being formed from a second material, the first material being galvanically incompatible with the second material and the first material being less noble than the second material; a non-conductive material disposed between the protective sheath and the airfoil so that they are electrically isolated from each other; a sacrificial anode in contact with the blade, wherein the sacrificial anode is formed from a third material that is less noble than the first material such that it will corrode before the first material if the non-conductive material disposed between the protective sheath and the airfoil is compromised and the first material and the second material are no longer electrically isolated from each other.

Abstract: An electroformed sheath for protecting an airfoil includes a sheath body and a mandrel insert is provided. The sheath body includes a leading edge. The sheath body includes a pressure side wall and an opposed suction side wall, which side walls meet at the leading edge and extend away from the leading edge to define a cavity between the side walls. The sheath body includes a head section between the leading edge and the cavity. The mandrel insert is positioned between the pressure side and suction side walls, and includes a generally wedge-shaped geometry. A method for protecting an airfoil includes: 1) securing a mandrel insert to a mandrel; 2) electroplating a sheath body onto the mandrel and the mandrel insert; 3) removing the mandrel from the sheath body so that a sheath cavity is defined within the sheath body; and 4) securing the airfoil within the sheath cavity.